[Elasticsearch - The Definitive Guide] Phrase Matching

match query type 중 phrase 에 대한 이해를 돕기 위해 기록 합니다.

원문링크)

https://www.elastic.co/guide/en/elasticsearch/guide/current/phrase-matching.html

원문 Snippet)

What Is a Phraseedit

For a document to be considered a match for the phrase “quick brown fox,” the following must be true:

• quick, brown, and fox must all appear in the field.
• The position of brown must be 1 greater than the position of quick.
• The position of fox must be 2 greater than the position of quick.

If any of these conditions is not met, the document is not considered a match.

Internally, the match_phrase query uses the low-level span query family to do position-aware matching. Span queries are term-level queries, so they have no analysis phase; they search for the exact term specified.

Thankfully, most people never need to use the span queries directly, as the match_phrasequery is usually good enough. However, certain specialized fields, like patent searches, use these low-level queries to perform very specific, carefully constructed positional searches.

다시 한번 정리 하면,

- position-aware matching 을 이용하는 span query

- 첫번째 term 에 대한 position에 의해 나머지 term 들의 matching position 은 quick의 position 보다 커야 합니다.